Sumflash: Mental Math Flash
Soroban-Style Number Trainer
Only for iPhone
Free · In‑App Purchases · Designed for iPhone. Not verified for macOS.
iPhone
Numbers flash one at a time—add them up in your head. No ads while numbers flash or while you answer. When you miss, see the running total and every carry.
Numbers appear on screen one at a time, each for just a moment. Add them all up in your head and enter the total. This is flash mental math, the way it's practiced with the soroban (Japanese abacus).
There are 30 levels, and you practice at the one you choose.
- See why you missed
After each answer, review every number that flashed along with the running total at that point. Numbers where a carry happened are highlighted, so you can spot exactly where you slipped. Replay the same problem, or replay it slowly.
- From 0.2 to 5.0 seconds
Set the speed yourself anywhere from 0.2 to 5.0 seconds per number.
- 30 levels
From 1 digit, 3 numbers, 1 second each, each level changes one thing at a time: more numbers, then faster, then more digits (up to 3 digits, 15 numbers, 0.5 seconds). Change your level anytime from the home screen. Already experienced? Pick a higher starting point on the first launch.
- A daily habit
Your home screen shows your streak: how many days in a row you've practiced. Miss just one day in a Monday-to-Sunday week and your streak stays alive. One set is five problems and takes just a few minutes.
Set a daily reminder at a time you choose (it stays quiet on days you've already practiced).
- Five themes
• Minimal: thin numbers on white
• Washi: Mincho numerals and a red seal
• Neon: glowing numbers
• Chalkboard: chalk numbers on green
• Sakura: rounded numbers on pale pink
Your records carry over when you change themes.
- For the whole family
Each profile keeps its own level, practice days, and records.
- Ranked play and leaderboards
One digit, ten numbers, a little faster each stage. Your fastest cleared display time goes to Game Center leaderboards (today, this week, all time; global and friends).
- Add, subtract, multiply, divide
Pick one from the tabs on the home screen. Addition and subtraction (mixed plus and minus) flash numbers one at a time; multiplication and division flash a single expression like "23 × 7". Each has its own 30 levels to choose from.
- Read aloud
Have numbers read aloud as they flash.
- Also
• An optional tick sound with each number (plays even in Silent mode; you can turn it off in Settings)
• Numbers simply appear and disappear, with no animation getting in the way
• Records are stored only on your device (if you're signed in to Game Center, only your best ranked-play time is sent to Apple for the leaderboard)
• No sign-in
- Premium (auto-renewable subscription)
• No ads
Monthly subscription. The price is shown in the app and may vary by region. It renews automatically every month and is charged to your Apple ID unless you cancel at least 24 hours before the renewal date. Cancel anytime in iPhone Settings › Apple ID › Subscriptions.
Premium only removes ads. Every other feature is free.
- About ads
Ads appear at the bottom of the home screen and between sets. No ads while numbers are flashing, while you're entering your answer, or while you're reviewing. Premium has no ads.
Terms of Use: https://fukuidinotech.github.io/sumflash-lp/en/terms.html
Privacy Policy: https://fukuidinotech.github.io/sumflash-lp/en/privacy.html
Contact: fukuidinotech@gmail.com
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
Sumflash is now available in German, French, Spanish, Italian, Portuguese, Korean, and Chinese (Simplified and Traditional).
The developer, Toru Fukui, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Used to Track You
The following data may be used to track you across apps and websites owned by other companies:
- Identifiers
- Usage Data
Data Linked to You
The following data may be collected and linked to your identity:
- Identifiers
- Usage Data
- Diagnostics
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Location
- Diagnostics
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Toru Fukui
- Size
- 14.7 MB
- Category
- Education
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
English and 9 more
- English, French, German, Italian, Japanese, Korean, Portuguese, Simplified Chinese, Spanish, Traditional Chinese
- Age Rating
4+
- 4+
- Contains
Advertising
- In-App Purchases
Yes
- Premium (Monthly) $1.99
- Copyright
- © 2026 Toru Fukui
